Mobile communications have changed the way people communicate and mobile phones have been transformed from a luxury item to an essential part of every day life. The use of mobile phones is today dictated by social situations, rather than hampered by location or technology. While voice connections fulfill the basic need to communicate, and mobile voice connections continue to filter even further into the fabric of every day life, the mobile Internet is the next step in the mobile communication revolution. The mobile Internet is poised to become a common source of everyday information, and easy, versatile mobile access to this data will be taken for granted.
As the number of electronic devices enabled for wired and/or mobile communications continues to increase, significant efforts exist with regard to making such devices more power efficient. For example, a large percentage of communications devices are mobile wireless devices and thus often operate on battery power. Additionally, transmit and/or receive circuitry within such mobile wireless devices often account for a significant portion of the power consumed within these devices. Moreover, in some conventional communication systems, transmitters and/or receivers are often power inefficient in comparison to other blocks of the portable communication devices. Accordingly, these transmitters and/or receivers have a significant impact on battery life for these mobile wireless devices.
Wireless local area network (WLAN) radio devices, such as those used in, for example, handheld wireless terminals, generally operate in the 2.4 GHz (2.4000-2.4835 GHz) Industrial, Scientific, and Medical (ISM) unlicensed band. Other radio devices, such as those used in cordless phones, may also operate in the ISM unlicensed band. While the ISM band provides a suitable low-cost solution for many of short-range wireless applications, it may also have some drawbacks when multiple users operate simultaneously. For example, because of the limited bandwidth, spectrum sharing may be necessary to accommodate multiple users. Multiple active users may also result in significant interference between operating devices. Moreover, in some instances, microwave ovens may also operate in this frequency spectrum and may produce significant interference or blocking signals that may affect WLAN transmissions.
The devices using the IEEE 802.11 physical layer (PHY) and medium access control (MAC) layer may be referred to as stations or access points, for example. The access points may enable distribution of data between endpoints. The MAC may also provide control frames for power management and time synchronization, for example. The access points may provide a time synchronization beacon to associated stations in an infrastructure basic service set (BSS). In an independent BSS, where stations are operating as peers, an algorithm may be defined that may enable each station to reset its time when it receives a synchronization value greater than its current value. The stations entering a power-saving mode may inform a WLAN device through the frame control field of a message, for example. The access point may then buffer transmissions to the station. A station may wake up periodically to receive beacon frames and be informed that it has buffered transmissions waiting and then request transmission. A station in active mode may be enabled to receive frames at any time during a contention-free period. On the other hand, a station in a power-save mode may periodically enter the active mode to receive beacons, broadcast, multicast, and buffered data frames.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.